Timing advance in new radio

ABSTRACT

According to one aspect of the present disclosure, a method for uplink synchronization is provided, wherein the method includes receiving, by a user equipment (UE), a radio resource control (RRC) message from a network, the RRC message comprising a first Timing Advance Group (TAG) identity (ID) and a second TAG ID different than the first TAG ID. The method also includes transmitting, by the UE, a first signal over a component carrier in accordance with a timing advance associated with the first TAG ID and a second signal over the component carrier in accordance with a timing advance associated with the second TAG ID.

TECHNICAL FIELD

The present disclosure relates to wireless communications, and inparticular embodiments, to systems and methods for performing uplinksynchronization.

BACKGROUND

Conventional synchronization techniques often require a user equipment(UE) to apply the same timing advance to its uplink transmissionscommunicated to the same base station over the same component carrier.Such techniques may be unsuitable for next generation wireless networks,where uplink transmissions over the same component carrier may travelthrough separate propagation paths, and thus have different propagationdelays. To solve the above issue, advanced uplink synchronizationtechniques are desired.

SUMMARY

Technical advantages are generally achieved, by embodiments of thisdisclosure which describe uplink synchronization methods for applyingseparate timing advances to different uplink transmissions.

According to one aspect of the present disclosure, a method for uplinksynchronization is provided, wherein the method includes receiving, by auser equipment (UE), a radio resource control (RRC) message from anetwork, the RRC message comprising a first Timing Advance Group (TAG)identity (ID) and a second TAG ID different than the first TAG ID. Themethod also includes transmitting, by the UE, a first signal over acomponent carrier in accordance with a timing advance associated withthe first TAG ID and a second signal over the component carrier inaccordance with a timing advance associated with the second TAG ID.

Optionally, in some embodiments of any of the preceding aspects, thefirst signal is transmitted to a first base station and the secondsignal is transmitted to a second base station.

Optionally, in some embodiments of any of the preceding aspects, thefirst signal and the second signal are transmitted to a same basestation using separate beams.

Optionally, in some embodiments of any of the preceding aspects, thefirst TAG ID and the second TAG ID are included in power controlinformation in the RRC message, the first TAG ID and the second TAG IDmapped to different path loss reference signals.

Optionally, in some embodiments of any of the preceding aspects, a pathloss reference signal mapped to the first TAG ID is indicated bydownlink control information (DCI) that schedules transmission of thefirst signal.

Optionally, in some embodiments of any of the preceding aspects, thefirst TAG ID and the second TAG ID are included in a TransmissionConfiguration Indicator (TCI) state configuration in the RRC message,the first TAG ID and the second TAG ID mapped to different TCI states.

Optionally, in some embodiments of any of the preceding aspects, a TCIstate mapped to the first TAG ID is indicated by downlink controlinformation (DCI) that schedules transmission of the first signal.

Optionally, in some embodiments of any of the preceding aspects, a TCIstate mapped to the first TAG ID is included in a control resource set(CORESET) associated with the first signal.

Optionally, in some embodiments of any of the preceding aspects, thefirst TAG ID and the second TAG ID are included in a Non-Zero PowerChannel State Information reference signal (NZP-CSI-RS) configuration inthe RRC message, the first TAG ID and the second TAG ID mapped todifferent NZP-CSI-RS resources.

Optionally, in some embodiments of any of the preceding aspects, anNZP-CSI-RS resource mapped to the first TAG ID is indicated by downlinkcontrol information (DCI) that schedules transmission of the firstsignal.

According to another aspect of the present disclosure, a method foruplink synchronization is provided, wherein the method includestransmitting, by a first base station of a network, an RRC message to aUE, the RRC message comprising a first TAG ID and a second TAG IDdifferent than the first TAG ID. The method also includes determining,by the first base station, a first timing advance associated with thefirst TAG ID for a first signal and a second timing advance associatedwith the second TAG ID for a second signal, the first signal and thesecond signal being transmitted from the UE over the same componentcarrier, and transmitting, by the first base station, the first timingadvance and the second timing advance to the UE.

Optionally, in some embodiments of any of the preceding aspects, themethod also includes receiving, by the first base station, the firstsignal from the UE in accordance with the first timing advance, andreceiving, by a second base station of the network, the second signalfrom the UE in accordance with the second timing advance.

Optionally, in some embodiments of any of the preceding aspects, themethod further includes receiving, by the first base station, the firstsignal and the second signal from the UE in accordance with separatebeams.

According to another aspect of the present disclosure, a UE is provided,wherein the UE comprises a non-transitory memory storage comprisinginstructions, and one or more processors in communication with thenon-transitory memory storage, wherein the one or more processorsexecute the instructions to receive an RRC message from a network, theRRC message comprising a first TAG ID and a second TAG ID different thanthe first TAG ID, and transmit a first signal over a component carrierin accordance with a timing advance associated with the first TAG ID anda second signal over the component carrier in accordance with a timingadvance associated with the second TAG ID.

Optionally, in some embodiments of any of the preceding aspects, the oneor more processors further execute the instructions to transmit thefirst signal to a first base station and transmit the second signal to asecond base station.

Optionally, in some embodiments of any of the preceding aspects, the oneor more processors further execute the instructions to transmit thefirst signal and the second signal to a same base station using separatebeams.

According to another aspect of the present disclosure, a first basestation is provided, wherein the first base station comprises anon-transitory memory storage comprising instructions, and one or moreprocessors in communication with the non-transitory memory storage,wherein the one or more processors execute the instructions to transmitan RRC message to a UE, the RRC message comprising a first TAG ID and asecond TAG ID different than the first TAG ID, determine a first timingadvance associated with the first TAG ID for a first signal and a secondtiming advance associated with the second TAG ID for a second signal,the first signal and the second signal being transmitted from the UEover the same component carrier, and transmit the first timing advanceand the second timing advance to the UE.

Optionally, in some embodiments of any of the preceding aspects, the oneor more processors further execute the instructions to receive the firstsignal from the UE in accordance with the first timing advance, thesecond signal being transmitted from the UE to a second base station ofthe network in accordance with the second timing advance.

Optionally, in some embodiments of any of the preceding aspects, the oneor more processors further execute the instructions to receive the firstsignal and the second signal from the UE in accordance with separatebeams.

Optionally, in some embodiments of any of the preceding aspects, thefirst TAG ID and the second TAG ID are included in power controlinformation for a PUSCH, the power control information included in anRRC message, the first TAG ID and the second TAG ID mapped to differentpath loss reference signals.

Optionally, in some embodiments of any of the preceding aspects, a pathloss reference signal mapped to the first TAG ID is indicated by DCIthat schedules transmission of the first signal.

Optionally, in some embodiments of any of the preceding aspects, thefirst TAG ID and the second TAG ID are included in a TCI stateconfiguration, the TCI state configuration included in an RRC message,the first TAG ID and the second TAG ID mapped to different TCI states.

Optionally, in some embodiments of any of the preceding aspects, a TCIstate mapped to the first TAG ID is indicated by DCI that schedulestransmission of the first signal.

Optionally, in some embodiments of any of the preceding aspects, a TCIstate mapped to the first TAG ID is included in a CORESET associatedwith the first signal.

Optionally, in some embodiments of any of the preceding aspects, thefirst TAG ID and the second TAG ID are included in a NZP-CSI-RSconfiguration, the NZP-CSI-RS configuration included in an RRC message,the first TAG ID and the second TAG ID mapped to different NZP-CSI-RSresources.

Optionally, in some embodiments of any of the preceding aspects, anNZP-CSI-RS resource mapped to the first TAG ID is indicated by DCI thatschedules transmission of the first signal.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an embodiment network architecture;

FIG. 2 is a flowchart of an embodiment uplink synchronization methodperformed by a user equipment (UE);

FIG. 3 is a diagram of uplink transmissions using beamforming;

FIG. 4 is an embodiment Timing Advance Group (TAG) configurationcomprising TAG IDs mapped to path loss reference signals;

FIG. 5 is an embodiment TAG configuration comprising TAG IDs mapped totransmission configuration indicator (TCI) states;

FIG. 6 is an embodiment TAG configuration comprising TAG IDs mapped toNon-Zero Power (NZP) Channel State Information Reference Signal (CSI-RS)resources;

FIG. 7 is an embodiment reference time selection method;

FIG. 8 is a flowchart of an embodiment uplink synchronization methodperformed by a base station;

FIGS. 9A-B illustrate block diagrams of embodiment devices; and

FIG. 10 illustrates a block diagram of an embodiment transceiver.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or not. The disclosure should in noway be limited to the illustrative implementations, drawings, andtechniques illustrated below, including the exemplary designs andimplementations illustrated and described herein, but may be modifiedwithin the scope of the appended claims along with their full scope ofequivalents.

Uplink transmissions are generally considered synchronized when theyarrive at a base station within a certain time period (e.g., one cyclicprefix (CP)) of one another. Otherwise they are consideredunsynchronized, and as a result interfere with each other. Userequipments (UEs) that communicate with a base station are usuallyscattered within a coverage area of the base station. Depending onspecific locations of each UE, uplink transmissions from the UEs mayexperience different propagation delays, which may cause significantvariations in their arrival times. To compensate for the difference inthe arrival times, a UE may adjust the timing advance of its uplinktransmission. Conventional synchronization techniques often require a UEto apply the same timing advance to its uplink transmissionscommunicated to the same base station over the same component carrier.Such techniques may be unsuitable for next generation wireless networks,where uplink transmissions over the same component carrier may travelthrough separate propagation paths, and thus have different propagationdelays. To solve the above issue, advanced uplink synchronizationtechniques are desired.

Embodiments of this disclosure provide mechanisms that permit a UE toapply different timing advances to uplink transmissions communicatedover the same component carrier. Uplink transmissions that arecommunicated through similar propagation paths over the same componentcarrier may be grouped together in what is referred to herein as aTiming Advance Group (TAG). A different timing advance may be configuredfor each TAG. Uplink transmissions belonging to the same TAG may use thesame timing advance. In some embodiments, a UE receives a TAGconfiguration from a network. The TAG configuration may be included in aradio resource control (RRC) message and may comprise multiple TAGidentities (IDs). Each TAG ID represents a TAG and is mapped to at leastone signal to be transmitted by the UE. After receiving the TAGconfiguration, the UE may transmit multiple signals to the network overthe same component carrier in accordance with timing advances associatedwith corresponding TAG IDs mapped to the respective signals. The signalsmay be transmitted to different base stations and/or different remoteradio heads (RRHs) connected to a common base station. Alternatively,the signals may be transmitted to the same base station using separatebeams. These and other aspects are discussed in greater detail as below.

FIG. 1 is a network 100 for communicating data. The network 100comprises a base station 110 having a coverage area 101, a plurality ofUEs 120, and a backhaul network 130. As shown, the base station 110establishes uplink (dashed line) and/or downlink (dotted line)connections with the user equipments (UEs) 120, which serve to carrysignals from the UEs 120 to the base station 110 and vice-versa. Signalscarried over the uplink/downlink connections may include traffic dataand reference signals communicated between the UEs 120, as well as datacommunicated to/from a remote-end (not shown) by way of the backhaulnetwork 130. As used herein, the term “base station” refers to anycomponent (or collection of components) configured to provide wirelessaccess to a network, such as a Transmit and Receive Point (TRP), anenhanced Node B (eNB), a next (fifth) generation (5G) NodeB (gNB), amacro-cell, a femtocell, a Wi-Fi access point (AP), or other wirelesslyenabled devices. The base station 110 may provide wireless access inaccordance with one or more wireless communication protocols, e.g., 5thgeneration new radio (5G_NR), long term evolution (LTE), LTE advanced(LTE-A), High Speed Packet Access (HSPA), Wi-Fi 802.11a/b/g/n/ac, etc.As used herein, the term “UE” refers to any component (or collection ofcomponents) capable of establishing a wireless connection with a basestation, such as a mobile device, a mobile station (STA), and otherwirelessly enabled devices. In some embodiments, the network 100 maycomprise various other wireless devices, such as relays, low powernodes, etc.

FIG. 2 is a flowchart of an embodiment method 200 for uplinksynchronization performed by a UE. At step 210, the UE receives a TAGconfiguration from a network. The TAG configuration comprises multipleTAG IDs including a first TAG ID and a second TAG ID, where the secondTAG ID is different than the first TAG ID. It is understood that two TAGIDs are purely for the purpose of illustration and it should beappreciated that more than two TAG IDs may be implemented based on thepresent disclosure.

At step 220, the UE transmits a first signal and a second signal over acomponent carrier in accordance with timing advances associated with afirst TAG ID and a second TAG ID, respectively. The UE may receive theTAG configuration from a base station of the network that communicateswith the UE. The base station may determine a corresponding timingadvance associated with each of the multiple TAG IDs, and send thetiming advances to the UE. The base station may estimate a propagationdelay between the base station and the UE, and may determine the timingadvance based thereon. For example, the timing advance may be a valuetwice the propagation delay. Due to mobility of the UE, the timingadvance may be dynamically adjusted by the base station in accordancewith propagation paths between a current location of the UE and the basestation. The UE may receive an initial timing advance from the basestation in a Random Access Response (RAR) command during a random accessprocedure. The RAR command may include at least a TAG ID and an initialtiming advance associated with the TAG ID. When the UE relocates, thebase station may estimate an updated timing advance, and send a MediaAccess Controls (MAC) Control Element (CE) to the UE. The MAC CE mayinclude the TAG ID and the updated timing advance. Alternatively, theMAC CE may include the TAG ID and a difference between the updatedtiming advance and the initial timing advance.

In order to extend cellular coverage and improve performance of signalreception, the network may adopt joint reception techniques, wheremultiple network devices in the same serving cell jointly receive andcombine signals transmitted from a UE. The signals transmitted from theUE to the multiple network devices may experience different propagationdelays. In one embodiment, the multiple network devices are basestations (sometimes known as Transmit and Receive Points (TRPs)) locatedin different positions. The UE transmits the first signal to a firstbase station, and transmits the second signal to a second base station.The first base station and the second base station may have the same NRcell ID. In another embodiment, the multiple network devices are RRHsseparately located but connected to a common base station. An RRH isgenerally a remotely located radio transceiver that is connected to abase station, and may include at least a radio frequency (RF) circuitfor the base station. The UE may transmit the first signal to a firstRRH, and transmit the second signal to a second RRH.

Both the UE and the base station may use beamforming to compensate pathloss of a wireless signal during a transmission, especially when thewireless signal is communicated at high frequencies (e.g., millimeterWave (mmW)). In one embodiment, the UE transmits the first signal andthe second signal to the same base station using separate beams. Inanother embodiment, the UE transmits the first signal to a first basestation using a first beam, and transmits the second signal to a secondbase station using a second beam.

FIG. 3 is a diagram of uplink transmissions using a beamformingtechnique. Beamforming may be used to improve both transmission (TX) andreception (RX) performance. As shown, a UE 320 transmits signals 331,333, 335 using TX beams 321, 323, 325 (respectively), and a base station310 receives the signals 331, 333, 335 using RX beams 311, 313, 315. Asused herein, the term “beam direction” refers to a radio antennapattern, or set of beamforming weights, that is used for directionalsignal transmission and/or reception. The terms “beam directions” and“beams” are used interchangeably herein. Although UE 320 transmitssignals to only one base station in the example depicted by FIG. 3, itshould be appreciated that UE 320 may transmit signals to another basestation (not shown in FIG. 3) using either the same TX beams or anotherset of TX beams.

Conventional synchronization techniques may map a TAG ID to a servingcell, so that uplink transmissions from a UE connected to the servingcell are configured with the same TAG ID and use the same timingadvance. For example, in 5G_NR, a TAG configuration is included in aradio resource control (RRC) message. The TAG configuration comprises aserving cell and a TAG ID associated with the serving cell. For example,a base station may transmit a SCellConfig information element to a UE toconfigure a serving cell. Tables 1A-1B show content of a SCellConfiginformation element defined in 3rd Generation Partnership Project (3GPP)protocol Release 15. As shown in Table 1A, the SCellConfig informationelement includes an index for the serving cell sCellIndex, and otherparameters sCellConfigCommon and sCellConfigDedicated. Specifically, asshown in Table 1B, sCellConfigDedicated includes a TAG ID. After the UEreceives the SCellConfig information element, whenever the UEcommunicates uplink transmissions to serving cell sCellIndex, the UEwill apply a timing advance associated with the TAG ID included inSCellConfig. The TAG configuration may comprise information of multipleserving cells and a corresponding TAG ID associated with each of themultiple serving cells. For example, in 3GPP protocol a base station maytransmit a parameter named sCellToAddModList to a UE to configuremultiple serving cells. The parameter sCellToAddModList may includemultiple SCellConfig information elements.

However, as already mentioned, uplink transmissions from a UE todifferent base stations, TRPs, or RRHs using either the same beam ordifferent beams within the same serving cell or on the same componentcarrier may experience different propagation delays. Thus, applyingdifferent timing advances to these uplink transmissions may bebeneficial to uplink synchronization. To this end, different TAGconfiguration methods are provided in this disclosure.

TABLE 1A SCellConfig ::=SEQUENCE { sCellIndex SCellIndex,sCellConfigCommon OPTIONAL, -- Cond ServingCellConfigCommon SCellAddsCellConfigDedicatedServingCellConfig OPTIONAL, -- Cond SCellAddMod ...}

TABLE 1B ServingCellConfig ::= SEQUENCE { ... tag-Id TAG-Id, ... }

In some embodiments, each TAG ID in a TAG configuration is mapped to acorresponding path loss reference signal. Prior to an uplinktransmission (e.g., an uplink transmission on either a Physical UplinkShared Channel (PUSCH) or a Physical Uplink Control Channel (PUCCH)),the UE may select a path loss reference signal for the uplinktransmission. The UE may follow a reference signal selection proceduresimilar to those described in 3rd Generation Partnership Project (3GPP)protocol 38.213 Section 7.1. The UE performs measurements using theselected path loss reference signal and adjusts power of the uplinktransmission in accordance with the performed measurements. Thus, a TAGID mapped to the selected path loss reference signal is associated withthe uplink transmission. Then the UE may apply a timing advanceassociated with the TAG ID to the uplink transmission.

FIG. 4 is an embodiment TAG configuration 410 comprising TAG IDs mappedto path loss reference signals. TAG configuration 410 includes N fields,each field indicating a different path loss reference signal. As shownin example 420, each field may include an ID of a path loss referencesignal and a TAG ID mapped to the path loss reference signal. Each fieldmay also include more information of the path loss reference signal. Inexample 430, if the path loss reference signal in a field is aSynchronization Signal Block (SSB), the field may include a location ofthe SSB (e.g., SSB index). In example 440, if the path loss referencesignal in a field is a Channel State Information Reference Signal(CSI-RS), the field may include a location of the CSI-RS (e.g., Non-ZeroPower (NZP) CSI-RS resource ID).

The TAG configuration may be included in power control information in anRRC message transmitted from the network to the UE, and may be encodedin Abstract Syntax Notation One (ASN.1) format. For example, the powercontrol information may include one or more information elements. Eachof the information elements may have a structure illustrated by Table 2Aand Table 2B. The PUSCH-PathlossReferenceRS information element in Table2A may be power control information for a PUSCH. The TAG ID included inthe PUSCH-PathlossReferenceRS information element is mapped to a pathloss reference signal indicated by this information element. ThePUCCH-PathlossReferenceRS information element in Table 2B may be powercontrol information for a PUCCH. The TAG ID included in thePUCCH-PathlossReferenceRS information element is mapped to a path lossreference signal indicated by this information element.

TABLE 2A PUSCH-PathlossReferenceRS ::= SEQUENCE {pusch-PathlossReferenceRS-Id PUSCH-PathlossReferenceRS-Id,referenceSignal CHOICE { ssb-Index SSB-Index, csi-RS-IndexNZP-CSI-RS-ResourceId  } pusch-tag-Id TAG-ID }

TABLE 2B PUCCH-PathlossReferenceRS ::= SEQUENCE {pucch-PathlossReferenceRS-Id PUCCH-PathlossReferenceRS-Id,referenceSignal CHOICE { ssb-Index SSB-Index, csi-RS-IndexNZP-CSI-RS-ResourceId } pucch-tag-Id TAG-ID }

In one embodiment, mapping between a path loss reference signal and aTAG ID is mandatory. For example, a UE may receive a TAG configurationonly including TAG IDs mapped to path loss reference signals. The UE maynot receive a TAG ID associated with a serving cell.

In another embodiment, the mapping between a path loss reference signaland a TAG ID is optional. For example, the UE may receive a SCellConfiginformation element which includes a TAG ID mapped to a serving cell(e.g., as illustrated in Tables 1A and 1B). If the UE does not receiveTAG IDs mapped to path loss reference signals, the UE may apply the TAGconfiguration included in the SCellConfig information element. If the UEreceive TAG IDs mapped to path loss reference signals, the UE may startusing these mappings, and ignore the TAG configuration included in theSCellConfig information element.

In some embodiments, each TAG ID in a TAG configuration is mapped to acorresponding transmission configuration indicator (TCI) state. A TCIstate usually indicates information of a TX beam that a PhysicalDownlink Control Channel (PDCCH) uses, such as Quasi-Co-Location (QCL)parameters of a Demodulation Reference Signal (DMRS) antenna port. FIG.5 is an embodiment TAG configuration 510 comprising TAG IDs mapped toTCI states. TAG configuration 510 includes N fields, each fieldindicating a different TCI state. As shown in example 520, each fieldmay include a TCI state ID and a corresponding TAG ID. Each field mayalso include some other information of a TCI state. In example 530, eachfield may include QCL type 1 and QCL type 2.

The TAG configuration including TAG IDs mapped to TCI states may beincluded in a TCI state configuration in an RRC message transmitted fromthe network to the UE, and may be encoded in ASN.1 format. For example,the TCI state configuration may include one or more TCI-Stateinformation elements. Each of the information elements may have astructure illustrated by Table 3. The TAG ID included in the TCI-Stateinformation element in Table 3 is mapped to a TCI state indicated bythis information element.

TABLE 3 TCI-State ::= SEQUENCE { tci-StateId TCI-StateId, qcl-Type1QCL-Info, qcl-Type2 QCL-Info OPTIONAL, -- Need R tci-tag-Id TAG-ID ... }

When a UE receives a TAG configuration including TAG IDs mapped to TCIstates, the UE may treat mapping between TAG IDs and TCI states as anoptional configuration. For example, the UE may receive aSCellConfiginformation element which includes a TAG ID mapped to aserving cell (e.g., as illustrated in Tables 1A and 1B). If the UE doesnot receive TAG IDs mapped to TCI states, the UE may apply the TAGconfiguration included in the SCellConfiginformation element. If the UEreceive TAG IDs mapped to TCI states, the UE may start using thesemappings, and ignore the TAG configuration included in theSCellConfiginformation element.

In one embodiment, during a time slot, the UE may receive a PDCCHlocated in a control resource set (CORESET), and a TCI state may havebeen assigned to the UE to decode the PDCCH. When the UE has an uplinktransmission to be communicated in this time slot, the UE may select aTAG ID mapped to the TCI state, and apply a timing advance associatedwith the TAG ID to the uplink transmission.

In another embodiment, an uplink transmission is scheduled by downlinkcontrol information (DCI) (e.g., DCI format 0-1) carried in a PDCCH. TheDCI may include a 3-bit field indicating a TCI state. The UE may selecta TAG ID mapped to the TCI state, and apply a timing advance associatedwith the TAG ID to the uplink transmission.

In some embodiments, each TAG ID in a TAG configuration is mapped to anNZP-CSI-RS resource, a type of CSI-RS used for channel measurements forthe purpose of reporting. FIG. 6 is an embodiment TAG configuration 610comprising TAG IDs mapped to NZP-CSI-RS resources. TAG configuration 610includes N fields, each field indicating a different NZP-CSI-RS resourcefrom an NZP-CSI-RS resource set. As shown in example 620, each field mayinclude an NZP-CSI-RS resource ID and a corresponding TAG ID. Each fieldmay not include an explicit NZP-CSI-RS resource ID. Instead, anNZP-CSI-RS resource ID may be indicated by a location of a field withinthe TAG configuration.

The TAG configuration including TAG IDs mapped to NZP-CSI-RS resourcesmay be included in a NZP-CSI-RS configuration in an RRC messagetransmitted from the network to the UE, and may be encoded in ASN.1format. For example, the NZP-CSI-RS configuration may include one ormore NZP-CSI-RS-Resource information elements. Each of the informationelements may have a structure illustrated by Table 4. The TAG IDincluded in the NZP-CSI-RS-Resource information element in Table 4 ismapped to a NZP-CSI-RS resource indicated by this information element.

TABLE 4 NZP-CSTRS-Resource ::= SEQUENCE { nzp-CSI-RS-ResourceIdNZP-CSI-RS-ResourceId, resourceMapping CSI-RS-ResourceMapping,nzp-CSTRS-tag-Id TAG-ID, ... }

When a UE receives a TAG configuration including TAG IDs mapped toNZP-CSI-RS resources, the UE may treat mapping between TAG IDs andNZP-CSI-RS resources as an optional configuration. For example, the UEmay receive a SCellConfiginformation element which includes a TAG IDmapped to a serving cell (e.g., as illustrated in Tables 1A and 1B). Ifthe UE does not receive TAG IDs mapped to NZP-CSI-RS resources, the UEmay apply the TAG configuration included in the SCellConfig informationelement. If the UE receive TAG IDs mapped to NZP-CSI-RS resources (e.g.,as illustrated in FIG. 6), the UE may start using these mappings, andignore the TAG configuration included in the SCellConfiginformationelement.

A UE generally uses an arrival time of a downlink radio frame as areference time for its uplink transmissions. By applying a timingadvance to an uplink transmission, the UE may transmit the uplinktransmission the timing advance earlier than the reference time. Forexample, in FIG. 7, a UE receives a downlink radio frame 701 from afirst base station at time 710. If a timing advance 730 has beenconfigured for an uplink radio frame 702 from the UE, then the UEtransmits uplink radio frame 702 at time 720.

In a joint reception case that involves multiple base stations, the UEmay receive a downlink radio frame 703 from a second base station attime 740. When the UE applies timing advances to its uplinktransmissions to the second base station, the UE may use time 740 as thereference. For example, if a timing advance 760 has been configured foran uplink radio frame 704 from the UE, then the UE may transmit uplinkradio frame 704 at time 750. Alternatively, the UE may use one of time710 and time 740 as the reference for uplink transmissions to both thefirst base station and the second base station. In this case, dependingon which reference is being used and which base station the uplinktransmission is transmitted to, the UE may adjust the timing advancesconfigured for the UE by considering a difference 780 between time 710and time 740. For instance, if time 740 is chosen as the reference time,timing advance 760 still applies to the transmission of uplink radioframe 704. However, uplink radio frame 702 should use a new timingadvance 770, which is equal to the sum of timing advance 730 and thedifference 780.

FIG. 8 is a flowchart of an embodiment method 800 for uplinksynchronization performed by a base station. At step 810, the basestation transmits a TAG configuration to the UE. The TAG configurationcomprises multiple TAG IDs including a first TAG ID and a second TAG ID,where the second TAG ID is different than the first TAG ID. At step 820,the base station determines multiple timing advances including a firsttiming advance for and the second timing advance. Each of the multipletiming advances is for a signal to be transmitted from the UE, and isassociated with one of the multiple TAG IDs. The first timing advanceassociated with the first TAG ID is determined for a first signal, andthe second timing advance associated with the second TAG ID isdetermined for a second signal, where the first signal and the secondsignal are to be transmitted from the UE over the same componentcarrier. At step 830, the base station transmits the multiple timingadvances to the UE. In one example, each of the multiple timing advancesmay be included in a RAR command during a random access procedure. Inanother example, each of the multiple timing advances may be included aMAC CE transmitted from the base station to the UE.

In one embodiment, the base station may receive the first signal fromthe UE in accordance with the first timing advance. Another base stationmay receive the second signal from the UE in accordance with the secondtiming advance. The base station and the other base station belong tothe same network. In another embodiment, the base station receives thefirst signal and the second signal from the UE using separate beams.

FIGS. 9A and 9B illustrate example devices that may implement themethods and teachings according to this disclosure. In particular, FIG.9A illustrates an example UE 910, and FIG. 9B illustrates an examplebase station 970.

As shown in FIG. 9A, the UE 910 includes at least one processing unit900. The processing unit 900 implements various processing operations ofthe UE 910. For example, the processing unit 900 could perform signalcoding, data processing, power control, input/output processing, or anyother functionality enabling the UE 910 to operate in the network. Theprocessing unit 900 may also be configured to implement some or all ofthe functionality and/or embodiments described in more detail above.Each processing unit 900 includes any suitable processing or computingdevice configured to perform one or more operations. Each processingunit 900 could, for example, include a microprocessor, microcontroller,digital signal processor, field programmable gate array, or applicationspecific integrated circuit.

The UE 910 also includes at least one transceiver 902. The transceiver902 is configured to modulate data or other content for transmission byat least one antenna or Network Interface Controller (NIC) 904. Thetransceiver 902 is also configured to demodulate data or other contentreceived by the at least one antenna 904. Each transceiver 902 includesany suitable structure for generating signals for wireless transmissionand/or processing signals received. Each antenna 904 includes anysuitable structure for transmitting and/or receiving wireless signals.One or multiple transceivers 902 could be used in the UE 910, and one ormultiple antennas 904 could be used in the UE 910. Although shown as asingle functional unit, a transceiver 902 could also be implementedusing at least one transmitter and at least one separate receiver.

The UE 910 further includes one or more input/output devices 906 orinterfaces. The input/output devices 906 permit interaction with a useror other devices in the network. Each input/output device 906 includesany suitable structure for providing information to or receivinginformation from a user, such as a speaker, microphone, keypad,keyboard, display, or touch screen, including network interfacecommunications.

In addition, the UE 910 includes at least one memory 908. The memory 908stores instructions and data used, generated, or collected by the UE910. For example, the memory 908 could store software instructions ormodules configured to implement some or all of the functionality and/orembodiments described above and that are executed by the processingunit(s) 900. Each memory 908 includes any suitable volatile and/ornon-volatile storage and retrieval device(s). Any suitable type ofmemory may be used, such as random access memory (RAM), read only memory(ROM), hard disk, optical disc, subscriber identity module (SIM) card,memory stick, secure digital (SD) memory card, and the like. It isunderstood that the components as shown in FIG. 9A is for the purpose ofillustration and the UE 910 may include part or all of the componentsillustrated in FIG. 9A.

As shown in FIG. 9B, the base station 970 includes at least oneprocessing unit 950, at least one transmitter 952, at least one receiver954, one or more antennas 956, at least one memory 958, and one or moreinput/output devices or interfaces 966. A transceiver, not shown, may beused instead of the transmitter 952 and receiver 954. A scheduler 953may be coupled to the processing unit 950. The scheduler 953 may beincluded within or operated separately from the base station 970. Theprocessing unit 950 implements various processing operations of the basestation 970, such as signal coding, data processing, power control,input/output processing, or any other functionality. The processing unit950 can also be configured to implement some or all of the functionalityand/or embodiments described in more detail above. Each processing unit950 includes any suitable processing or computing device configured toperform one or more operations. Each processing unit 950 could, forexample, include a microprocessor, microcontroller, digital signalprocessor, field programmable gate array, or application specificintegrated circuit. It is understood that the components as shown inFIG. 9B is for the purpose of illustration and the base station 970 mayinclude part or all of the components illustrated in FIG. 9B.

Each transmitter 952 includes any suitable structure for generatingsignals for wireless transmission to one or more UEs or other devices.Each receiver 954 includes any suitable structure for processing signalsreceived from one or more UEs or other devices. Although shown asseparate components, at least one transmitter 952 and at least onereceiver 954 could be combined into a transceiver. Each antenna 956includes any suitable structure for transmitting and/or receivingwireless or wired signals. Although a common antenna 956 is shown hereas being coupled to both the transmitter 952 and the receiver 954, oneor more antennas 956 could be coupled to the transmitter(s) 952, and oneor more separate antennas 956 could be coupled to the receiver(s) 954.Each memory 958 includes any suitable volatile and/or non-volatilestorage and retrieval device(s) such as those described above inconnection to the UE 910. The memory 958 stores instructions and dataused, generated, or collected by the base station 970. For example, thememory 958 could store software instructions or modules configured toimplement some or all of the functionality and/or embodiments describedabove and that are executed by the processing unit(s) 950.

Each input/output device 966 permits interaction with a user or otherdevices in the network. Each input/output device 966 includes anysuitable structure for providing information to or receiving/providinginformation from a user, including network interface communications.

FIG. 10 illustrates a block diagram of a transceiver 1000 adapted totransmit and receive signaling over a telecommunications network. Thetransceiver 1000 may be installed in a host device. As shown, thetransceiver 1000 comprises a network-side interface 1002, a coupler1004, a transmitter 1006, a receiver 1008, a signal processor 1010, anda device-side interface 1012. The network-side interface 1002 mayinclude any component or collection of components adapted to transmit orreceive signaling over a wireless or wireline telecommunicationsnetwork. The coupler 1004 may include any component or collection ofcomponents adapted to facilitate bi-directional communication over thenetwork-side interface 1002. The transmitter 1006 may include anycomponent or collection of components (e.g., up-converter, poweramplifier, etc.) adapted to convert a baseband signal into a modulatedcarrier signal suitable for transmission over the network-side interface1002. The receiver 1008 may include any component or collection ofcomponents (e.g., down-converter, low noise amplifier, etc.) adapted toconvert a carrier signal received over the network-side interface 1002into a baseband signal. The signal processor 1010 may include anycomponent or collection of components adapted to convert a basebandsignal into a data signal suitable for communication over thedevice-side interface(s) 1012, or vice-versa. The device-sideinterface(s) 1012 may include any component or collection of componentsadapted to communicate data-signals between the signal processor 1010and components within the host device (e.g., the processing system 1200,local area network (LAN) ports, etc.).

The transceiver 1000 may transmit and receive signaling over any type ofcommunications medium. In some embodiments, the transceiver 1000transmits and receives signaling over a wireless medium. For example,the transceiver 1000 may be a wireless transceiver adapted tocommunicate in accordance with a wireless telecommunications protocol,such as a cellular protocol (e.g., LTE, etc.), a wireless local areanetwork (WLAN) protocol (e.g., Wi-Fi, etc.), or any other type ofwireless protocol (e.g., Bluetooth, near field communication (NFC),etc.). In such embodiments, the network-side interface 1002 comprisesone or more antenna/radiating elements. For example, the network-sideinterface 1002 may include a single antenna, multiple separate antennas,or a multi-antenna array configured for multi-layer communication, e.g.,single input multiple output (SIMO), multiple input single output(MISO), multiple input multiple output (MIMO), etc. In otherembodiments, the transceiver 1000 transmits and receives signaling overa wireline medium, e.g., twisted-pair cable, coaxial cable, opticalfiber, etc. Specific processing systems and/or transceivers may utilizeall of the components shown, or only a subset of the components, andlevels of integration may vary from device to device.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method for uplink synchronization, the methodcomprising: receiving, by a user equipment (UE), a radio resourcecontrol (RRC) message from a network, the RRC message comprising a firstTiming Advance Group (TAG) identity (ID) and a second TAG ID differentthan the first TAG ID, wherein the first TAG ID and the second TAG IDare configured according to at least one of following options: 1) thefirst TAG ID and the second TAG ID are included in power controlinformation in the RRC message, wherein the first TAG ID and the secondTAG ID are mapped to different path loss reference signals; 2) the firstTAG ID and the second TAG ID are included in a TransmissionConfiguration Indicator (TCI) state configuration in the RRC message,wherein the first TAG ID and the second TAG ID are mapped to differentTCI states; or 3) the first TAG ID and the second TAG ID are included ina Non-Zero Power Channel State Information reference signal (NZP-CSI-RS)configuration in the RRC message, wherein the first TAG ID and thesecond TAG ID are mapped to different NZP-CSI-RS resources; andtransmitting, by the UE, a first signal over a component carrier inaccordance with a timing advance associated with the first TAG ID and asecond signal over the component carrier in accordance with a timingadvance associated with the second TAG ID.
 2. The method of claim 1,wherein the first signal is transmitted to a first base station and thesecond signal is transmitted to a second base station.
 3. The method ofclaim 1, wherein the first signal and the second signal are transmittedto a same base station using separate beams.
 4. The method of claim 1,wherein a path loss reference signal mapped to the first TAG ID isindicated by downlink control information (DCI) that schedulestransmission of the first signal.
 5. The method of claim 1, wherein aTCI state mapped to the first TAG ID is indicated by downlink controlinformation (DCI) that schedules transmission of the first signal. 6.The method of claim 1, wherein a TCI state mapped to the first TAG ID isincluded in a control resource set (CORESET) associated with the firstsignal.
 7. The method of claim 1, wherein an NZP-CSI-RS resource mappedto the first TAG ID is indicated by downlink control information (DCI)that schedules transmission of the first signal.
 8. A method for uplinksynchronization, the method comprising: transmitting, by a first basestation of a network, a radio resource control (RRC)message to a userequipment (UE), the RRC message comprising a first Timing Advance Group(TAG) identity (ID) and a second TAG ID different than the first TAG ID,wherein the first TAG ID and the second TAG ID are configured accordingto at least one of following options: 1) the first TAG ID and the secondTAG ID are included in power control information in the RRC message,wherein the first TAG ID and the second TAG ID are mapped to differentpath loss reference signals; 2) the first TAG ID and the second TAG IDare included in a Transmission Configuration Indicator (TCI) stateconfiguration in the RRC message, wherein the first TAG ID and thesecond TAG ID are mapped to different TCI states; or 3) the first TAG IDand the second TAG ID are included in a Non-Zero Power Channel StateInformation reference signal (NZP-CSI-RS) configuration in the RRCmessage, wherein the first TAG ID and the second TAG ID are mapped todifferent NZP-CSI-RS resources; determining, by the first base station,a first timing advance associated with the first TAG ID for a firstsignal and a second timing advance associated with the second TAG ID fora second signal, the first signal and the second signal beingtransmitted from the UE over the same a component carrier; andtransmitting, by the first base station, the first timing advance andthe second timing advance to the UE.
 9. The method of claim 8, furthercomprising: receiving, by the first base station, the first signal fromthe UE in accordance with the first timing advance; and receiving, by asecond base station of the network, the second signal from the UE inaccordance with the second timing advance.
 10. The method of claim 8,further comprising: receiving, by the first base station, the firstsignal and the second signal from the UE in accordance with separatebeams.
 11. A user equipment (UE) comprising: a non-transitory memorystorage comprising instructions; and one or more processors incommunication with the non-transitory memory storage, wherein the one ormore processors execute the instructions to: receive a radio resourcecontrol (RRC) message from a network, the RRC message comprising a firstTiming Advance Group (TAG) identity (ID) and a second TAG ID differentthan the first TAG ID, wherein the first TAG ID and the second TAG IDare configured according to at least one of following options: 1) thefirst TAG ID and the second TAG ID are included in power controlinformation in the RRC message, wherein the first TAG ID and the secondTAG ID are mapped to different path loss reference signals; 2) the firstTAG ID and the second TAG ID are included in a TransmissionConfiguration Indicator (TCI) state configuration in the RRC message,wherein the first TAG ID and the second TAG ID are mapped to differentTCI states; or 3) the first TAG ID and the second TAG ID are included ina Non-Zero Power Channel State Information reference signal (NZP-CSI-RS)configuration in the RRC message, wherein the first TAG ID and thesecond TAG ID are mapped to different NZP-CSI-RS resources; and transmita first signal over a component carrier in accordance with a timingadvance associated with the first TAG ID and a second signal over thecomponent carrier in accordance with a timing advance associated withthe second TAG ID.
 12. The UE of claim 11, wherein the one or moreprocessors further execute the instructions to transmit the first signalto a first base station and transmit the second signal to a second basestation.
 13. The UE of claim 11, wherein the one or more processorsfurther execute the instructions to transmit the first signal and thesecond signal to a same base station using separate beams.
 14. A firstbase station of a network, the first base station comprising: anon-transitory memory storage comprising instructions; and one or moreprocessors in communication with the non-transitory memory storage,wherein the one or more processors execute the instructions to: transmita radio resource control (RRC)message to a user equipment (UE), the RRCmessage comprising a first Timing Advance Group (TAG) identity (ID) anda second TAG ID different than the first TAG ID, wherein the first TAGID and the second TAG ID are configured according to at least one offollowing options: 1) the first TAG ID and the second TAG ID areincluded in power control information in the RRC message, wherein thefirst TAG ID and the second TAG ID are mapped to different path lossreference signals; 2) the first TAG ID and the second TAG ID areincluded in a Transmission Configuration Indicator (TCI) stateconfiguration in the RRC message, wherein the first TAG ID and thesecond TAG ID are mapped to different TCI states; or 3) the first TAG IDand the second TAG ID are included in a Non-Zero Power Channel StateInformation reference signal (NZP-CSI-RS) configuration in the RRCmessage, wherein the first TAG ID and the second TAG ID are mapped todifferent NZP-CSI-RS resources; determine a first timing advanceassociated with the first TAG ID for a first signal and a second timingadvance associated with the second TAG ID for a second signal, the firstsignal and the second signal being transmitted from the UE over the samea component carrier; and transmit the first timing advance and thesecond timing advance to the UE.
 15. The first base station of claim 14,wherein the one or more processors further execute the instructions toreceive the first signal from the UE in accordance with the first timingadvance, the second signal being transmitted from the UE to a secondbase station of the network in accordance with the second timingadvance.
 16. The first base station of claim 14, wherein the one or moreprocessors further execute the instructions to receive the first signaland the second signal from the UE in accordance with separate beams. 17.The first base station of claim 14, wherein a path loss reference signalmapped to the first TAG ID is indicated by downlink control information(DCI) that schedules transmission of the first signal.
 18. The firstbase station of claim 14, wherein a TCI state mapped to the first TAG IDis indicated by downlink control information (DCI) that schedulestransmission of the first signal.
 19. The first base station of claim14, wherein a TCI state mapped to the first TAG ID is included in acontrol resource set (CORESET) associated with the first signal.
 20. Thefirst base station of claim 14, wherein an NZP-CSI-RS resource mapped tothe first TAG ID is indicated by downlink control information (DCI) thatschedules transmission of the first signal.
 21. The method of claim 1,wherein both the first TAG ID and the second TAG ID are assigned to thecomponent carrier.
 22. The method of claim 8, wherein both the first TAGID and the second TAG ID are assigned to the component carrier.
 23. TheUE of claim 11, wherein both the first TAG ID and the second TAG ID areassigned to the component carrier.
 24. The first base station of claim14, wherein both the first TAG ID and the second TAG ID are assigned tothe component carrier.